Audition Frequency and Amplitude Audition the sense of

Audition Frequency and Amplitude § Audition § the sense of hearing § Frequency § the number of complete wavelengths that pass a point in a given time = pitch § Pitch (wave frequency, Hz) § High frequency = high pitch § low frequency = low pitch

Amplitude: height of sound wave = loudness of sound Ø Timbre: quality, complexity of sound Ø Average human: hears tones from 20 Hz to 20, 000 Hz. Ø Women tend to hear higher frequencies Ø Theory: men = Louder activities more often… Ø

The Intensity of Some Common Sounds

From Waves to Sound § Outer Ear § § Middle Ear § § § Channels sound wave through auditory canal to eardrum Eardrum: Membrane/ converts wave to vibrations Vibrations pass through piston (hammer, anvil, stirrup: smallest bones in human body!) piston concentrates vibrations of the eardrum on the cochlea’s oval window Inner Ear § § Cochlea: converts vibrations into neural activity (vibration = ripples in basilar membrane fluid Bending hair cells = auditory neural impulse

In other words… Ø From sound waves to vibrations to fluid waves to neural impulse to auditory cortex (temporal lobe) = hearing!

Hair Cells: Basilar Membrane

How do we discern pitch? § Place Theory § Specific places along the basilar membrane match a tone with a particular pitch § Frequency Theory § rate of sound wave = rate of neural impulses to the brain (# of neural impulses determines pitch) ex. 100 sound waves/second = 100 neural impulses = pitch)

How We Locate Sounds Ø Brain analyzes differences in what is heard by each ear to determine where sound is coming from… (3 dimensional)

Hearing Loss 1. 2. 3. 4. 5. Most common physical disability 35 million Americans (500 million worldwide) Recent study: 60% of American college students suffer from high frequency hearing loss. Each 5 db increase, time it takes for permanent damage cut in half (after 85) Men: greater degree of hearing loss at every age (loud music or changes in cochlea that restrict blood supply to neural elements? )

Audition § Conduction Hearing Loss § § caused by damage to the mechanical system that conducts sound waves to the cochlea (Ear drum, hammer, anvil, stirrup) Nerve Hearing Loss § hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve (hairs in basilar membrane not regenerative)

Tinnitus Ø Damage to auditory ear (ringing in ears) l l l Advanced case is incapacitating Shell shock (combat zones) tinnitus masker: “ocean waves or radio static”

Helen Keller Ø What would be more difficult, being blind or deaf? Ø “…deafness to be a much greater handicap than blindness… Blindness cuts people off from things. Deafness cuts people off from people. ”

Cochlear Implants Ø Nerve deafness Ø “bionic ear” Ø Stimulates sites on auditory nerve

Audition § Amplitude required for perception relative to 20 -29 year-old group Older people tend to hear low frequencies well but suffer hearing loss for high frequencies 1 time 10 times 1000 times 32 64 128 256 512 1024 2048 4096 8192 16384 Frequency of tone in waves per second Low Pitch High

True or False? 1. Hard of hearing people need all sounds amplified. 2. Blind musicians are more likely than sighted ones to develop perfect pitch. 3. Deaf people’s auditory cortex becomes responsive to touch and visual input. Ø Sensory Compensation / plasticity

Touch Ø Skin senses: pressure, warmth, cold, pain Ø Which is the only sensation identifiable with skin receptors? l Pressure Ø The Rubber hand illusion (demo)

Touch

Pain Ø Pain = sensation + brain + expectation Ø “No brain, no pain” Ø More complex / no one stimulus / neural cord, no special receptors Ø Research shows extent of pain is more influential than duration (medical procedures)

Pain § Gate-Control Theory § § Theory: spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain Small nerve fibers: conduct pain signals Small nerve fibers open / activate neural gate Large nerve fibers close gate (shut off pain)

Chronic Pain Ø Pain= physiological and psychological Ø Treat by stimulating large neural fibers (to close the gate…) l Acupuncture, massage, electrical stimulation) Ø 1 in 6 Americans: 100 billion total expenses

Reactions to pain. . Ø Why do we rub something when we hurt it? l Create competing stimulation that will block some of the pain impulses… (“Makes it feel better…”)

Taste § Taste Sensations § § § sweet sour salty Bitter Umami (meaty taste) monosodium glutamate Sensory Interaction § § the principle that one sense may influence another (all senses) Ex: the smell of food influences its taste

Taste: A Chemical Sense Ø Each bump on your tongue = 200 taste buds Ø Taste sensitivity decreases with age Ø Sensory interaction: taste + texture +smell = flavor Ø T-F You can taste without your tongue. (Taste receptors in back and roof of mouth. )

New Studies Ø Tongue and taste: Place theory outdated Ø Taste is comprehensive over tongue

Senses Influence Each Other… § Sensory Interaction § § the principle that one sense may influence another (all senses) Ex: the smell of food influences its taste Synaesthesia (“to perceive together”) § joining of senses / one sense stimulates another § Feels shapes when taste / smell food § See colors in response to pain § Most common: see numbers / letters in colors § Recent study: 1 in 2, 000 - 1 male to 6 female § Theory: cross-activation of adjacent brain regions

Smell Olfaction Ø A chemical sense Ø Process Ø l l l Molecules of substance / air / 5 million receptor cells @ top of each nasal cavity Impulse sent to brain through axon fibers Odors recognized individually Odor molecules / neural receptors (key and lock) 10, 000 odors detected! Peak at early adulthood Olfactory bulb > amygdala > hippocampus > cortex (why smell evokes emotions, memories)

Smell Olfactory nerve Olfactory bulb Nasal passage Receptor cells in olfactory membrane

Gender and Senses Detecting men from women: smell Ø Research confirms: “hands, breath and shirts”Ø can distinguish the genders (pheromones) Ø Women better “sniffers” than men Ø

Age, Sex and Sense of Smell Number of correct answers Women and young adults have best sense of smell 4 Women 3 Men 2 0 10 -19 20 -29 30 -39 40 -49 50 -59 60 -69 Age Group 70 -79 80 -89 90 -99

Body Position and Movement (Sensorimotor Coordination) § Kinesthesis § § the system for sensing the position and movement of individual body parts Vestibular Sense § § § Monitors head (and thus bodies) movement Sense of balance (equalibrium) Inner ear: semicircular canals, vestibular sacs = fluid = hair-like receptors = impulse to cerebellum (Vertigo)

Make sense now…?